Why do the new Ex Machina woofers have a strange surround
Discovering Purifi Ushindi Drivers and Their Unique Technology
Source Linkedin Ex Machina SoundWorks
The new Ex Machina Terra and Gravity speakers don't go unnoticed. And there's a reason for that: their woofers feature a totally unusual, almost "crumpled" suspension, very different from conventional loudspeakers.
However, this strange design has nothing aesthetic about it. Behind this atypical geometry lies one of the most ambitious loudspeaker technologies of recent years: Purifi Ushindi drivers.
And yes: these are indeed the famous woofers that equip the new Terra as well as the Gravity subwoofers.
Terra and Gravity: A System Designed as a Coherent Whole
Unlike many monitoring systems where the subwoofer is added "on top," the new Terra and Gravity were designed as a true integrated 2.2 system.
The Terra are the main speakers: 3-way coaxial monitors intended for mixing, mastering, and demanding immersive environments.
The Gravity, meanwhile, are passive subwoofers specifically dedicated to the Terra. They extend the bass response down to extremely low frequencies while increasing the overall headroom of the system.
Ex Machina notably announces:
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an extension down to 20 Hz at -6 dB,
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a phase-coherent LR4 crossover,
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and an integration designed as a true point source
And at the heart of this system are the famous Purifi woofers.
A Very Particular Suspension… For a Very Precise Reason
The “Neutral Surround” geometry developed by Purifi aims to maintain a more constant radiating surface during speaker excursion. source: Purifi-audio.com
What immediately stands out about Purifi drivers is this unusually shaped suspension.
Purifi calls this technology “Neutral Surround Geometry.” The goal is to solve a problem rarely discussed in the world of loudspeakers: the variation of the radiating surface during large diaphragm excursions.
On a conventional woofer, when the diaphragm moves strongly forward or backward, the effective surface that radiates sound changes slightly. This can generate distortion and intermodulation, especially in the midrange.
The very specific geometry of Purifi aims precisely to maintain a more constant radiating surface during excursion.
This is what gives this peculiar appearance to the woofers used in the Terra and Gravity.
An Obsession with Distortion Reduction
Purifi is not an esoteric audio brand. The company is best known for its extremely scientific approach to sound reproduction.
The company was co-founded by Bruno Putzeys, also known for his work on Hypex NCore and Eigentakt amplification, and Kii speakers.
With Ushindi, Purifi explains having redesigned the loudspeaker "from scratch" to identify and correct the main sources of non-linearity:
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inductance variation,
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hysteresis,
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motor asymmetry,
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dynamic compression,
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excursion-related distortion,
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intermodulation distortion.
The result: extremely low distortion levels, even at high sound levels.
Impressive Measured Performance
Purifi woofers are known for their exceptionally low distortion levels, even at high SPL.
For several years, Purifi loudspeakers have greatly intrigued measurement and acoustic design enthusiasts.
Various independent measurements published by technical reviewers and laboratories show particularly low distortion levels, even in conditions where many loudspeakers begin to significantly degrade.
It is precisely this pursuit of linearity that explains why many high-end manufacturers are now interested in Purifi drivers.
Why This Is Particularly Interesting in Terra + Gravity
In a high-end monitoring system, the bass is not just about "having low end." It also directly influences midrange clarity, transient perception, and the stability of the sound image.
Very linear woofers notably allow for:
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cleaner bass,
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less lingering sound,
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less intermodulation in the low-mids,
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and better readability at high SPL.
This is exactly the type of approach Ex Machina seems to be pursuing with the Terra + Gravity combination: a system capable of very high technical performance while maintaining temporal coherence and low distortion.
Loudspeakers That Intrigue the Entire Audio Industry
For several years, Purifi woofers have become extremely popular with many high-end manufacturers, acoustical engineers, and demanding DIY enthusiasts.
The reason is quite simple: the measured performances are truly impressive.
But beyond the numbers, what makes Ushindi drivers particularly interesting is their design philosophy: rather than accepting certain historical limitations of dynamic loudspeakers, Purifi methodically attempts to eliminate them.
And evidently, Ex Machina shares precisely this vision.
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